my quick sort is not running............plz see for the problem

final.c

#include<stdio.h>
int n;
 main()
{
	int data[20],i;
		scanf("%d",&n);
	fflush(stdin);
	for(i=0;i<n;i++)
	{
		scanf("%d",&data[i]);
	}
	fflush(stdin);
	qsort(data,0,n-1);
		for(i=0;i<n;i++)
	{
		printf("%d  ",data[i]);
	}

}
qsort(data,start,end)
int data[],start,end;
{
	int p;
	if(start>=end)return;
	else {
	p=partition(data,start,end);
	qsort(data,start,p);
	qsort(start,p+1,end);}
}
int partition(data,left,right)
int data[],left,right;
{
	int i=left,j=right,pivot=data[left];
	int temp;
	while(i<j){
	while((i<j)&&(data[i]<pivot))i++;
	while((i<j)&&(data[j]>=pivot))j--;
	if(i<j){
		temp=data[i];
		data[i]=data[j];
		data[j]=temp;}


	}

	if(data[j]<=pivot)
        return(j);
	else
	return(j-1);

}